1. Field of the Invention
The present invention relates to a method and apparatus for raise bore drilling and lining of a borehole, more specifically to bore holes drilled for use in the mining industry.
2. Description of the Prior Art
Raise bore drilling has been used in the mining industry for many years and has been successful in virtually all types of rock. Modern raise bore drilling machines are capable of boring a pilot hole of up to 1000 meters and then reaming the pilot hole out to between 3 and 20 feet. Prior to the drilling of the pilot hole, information relating to the bore bole (i.e. location, start and end co-ordinates, size of hole, start-and-break-through mine levels, and the type of rock) are required to determine the size of raise drilling machine required, size of reamer, length of hole, and the size and number of drill rods required to complete the bore hole formation. Once this information is ascertained, the layout of the drilling apparatus is calculated and the drilling station is set up.
The first stage of borehole drilling involves the creation of a pilot hole. The piloting process generally begins by assembling a pilot bit, roller bit stabilizer, one or two ribbed stabilizers and loading the assembly into the raise drill. On drilling, the hole is flushed with a fluid medium, typically water, to flush cuttings away from the pilot bit. The resultant slurry is forced up through the drilled hole around the outside of the drill and is piped away from the raise drill by means known to one skilled in the art. Typically, a new drill rod is added after each live feet of drilling is completed, however lesser drill rod lengths are also used, The pilot process continues until the pilot bit breaks through at a lower level of the mine.
The second stage involves the replacement of the pilot bit with a reamer to enlarge a portion of the pilot hole. Generally the reamer is positioned such that it is adjacent to the surface of the rock face and is loaded to the tension required to force the reamer cutters into the rock during rotation of the drill string. Typically, after each drill rod length of reaming is complete, a drill rod is removed and the process is repeated until the reamer is immediately below the raise drill set up rail, At this point the reamer is removed and the borehole is completed.
The third stage involves lining of the borehole with a material such as cement to guard against the crosion and potential collapse of the borehole walls. Once the reamer and drilling equipment are removed, a lining delivery equipment is set up. Typically, this process involves the use of a separate device under remote control in order to avoid an operator having to descend into the boreholes. Several Systems exist for the application of this lining, such as preformed liner sleeves, shuttering, and a spray-on apparatus. However, each is an independent system to the apparatus used for the drilling of the borehole, This arrangement has disadvantages in that set-up time is required for both the drilling apparatus and lining delivery equipment. Accordingly, the use of two separate and independent systems in the creation of a borehole, one for drilling and one for lining, can require two crews and two sets of equipment. This method can be particularly time consuming and costly.
In the art, Canadian Patent 1,308,249 describes a process for the lining or boreholes involving an apparatus for the remote spraying of cement on the walls of a bore hole. This patent focuses solely on the lining of the borehole once the borehole has been created. Canadian Patent 1,251,475 teaches a raise bore mining method; however, the patent does not discuss the lining of the bore itself.
It is an object of the present invention to provide a drilling system and method to obviate or mitigate at least some of the above-mentioned disadvantages.